Bug 2460679 (CVE-2026-31509)

Summary: CVE-2026-31509 kernel: nfc: nci: fix circular locking dependency in nci_close_device
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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OS: Linux   
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A flaw was found in the Linux kernel, specifically within the Near Field Communication (NFC) NCI subsystem. A circular locking dependency can occur when the `nci_close_device()` function attempts to flush work queues while holding a lock that can be re-acquired by a work queue function. This improper handling of locks can lead to a system hang, resulting in a denial of service (DoS).
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Description OSIDB Bzimport 2026-04-22 15:04:59 UTC
In the Linux kernel, the following vulnerability has been resolved:

nfc: nci: fix circular locking dependency in nci_close_device

nci_close_device() flushes rx_wq and tx_wq while holding req_lock.
This causes a circular locking dependency because nci_rx_work()
running on rx_wq can end up taking req_lock too:

  nci_rx_work -> nci_rx_data_packet -> nci_data_exchange_complete
    -> __sk_destruct -> rawsock_destruct -> nfc_deactivate_target
    -> nci_deactivate_target -> nci_request -> mutex_lock(&ndev->req_lock)

Move the flush of rx_wq after req_lock has been released.
This should safe (I think) because NCI_UP has already been cleared
and the transport is closed, so the work will see it and return
-ENETDOWN.

NIPA has been hitting this running the nci selftest with a debug
kernel on roughly 4% of the runs.